Weird Weather Behavior: Winter Makes Us Love, Summer Makes Us Violent

We all know that sunny days make us happy -- but did you know that they also make us gamble? And that warm weather leads to both less sexual activity and higher incidents of depression? Weather affects human behavior in stronger, stranger ways that we realize, and this infographic from GB Energy Supply lays out some of the strangest:

Most of these behaviors are linked to extreme weather, like blistering temperatures or blustery storms. Most of them happen in particular seasons. Many happen in scorching heat. The most damaging ones happen in frigid cold, save for the increase of suicides happening between spring and summer. Here’s the science behind a few of these relationships.

A 2014 study in PLOS ONE had 133 German college students review mug shots of people who had been arrested. The researchers separated the students into rooms of varying temperatures and asked them to describe the type and impulsiveness of the crime committed by the person in the headshot. When students were in cold rooms, they were more likely to see criminals as cold-blooded offenders with premeditated crimes. When students were in hot rooms, they thought the criminals were hotheads who committed impulsive crimes. That result is surprising for its starkness, but not surprising: there are many studies that demonstrate how changes in temperature directly influence our judgement, including this 2008 one in Scienceusing coffee.

A 2012 Journal of Consumer Researchstudy did four different experiments to test this. Researchers gave 53 male and female graduate students either hot or iced tea and asked them to fill out a survey about movie preferences. The students overwhelmingly chose romantic movies when holding cold drinks. They didn’t express a preference for any other film genre. A few didn’t prefer romantic movies when holding their cold drink, but that was most likely because they didn’t associate romantic movies with warm fuzzy feelings at all. Try it out yourself the next time you browse your Netflix queue.

A 2016 study published by the Association for Psychological Science analyzed daily lottery purchases in 174 New York City neighborhoods. Researchers calculated all wins and losses for NYC teams during regular and postseason games between 2011 and 2012. After weighing that data against a calculation for the average for amount of sunshine per day, researchers found “large prediction errors resulting from sunshine could shift daily purchase rates up or down by up to 0.5%.” That may sound small, but it was consistent across every single NYC neighborhood regardless of demographics or wealth. Also a small percentage here is relative, since "approximately $160,000 more is spent on lottery gambling relative to an average day," the researchers add. "These results reveal a remarkable malleability to human risk taking: people's gambling behavior is shaped by unexpected, but incidental outcomes in their environment."

This conclusion may not sound surprising, but what is surprising is the amount of data that backs it up. A 2013 quantitative synthesis in Science looked at 60 primary studies with 45 different data sets. Those studies looked at time periods from 10,000 BCE to today and drew data from all over the world. After sorting the data to compare individual countries during different time periods, the researchers found a distinct correlation between rising global temperatures and increased in crime all over the world particularly after the 1950s. The authors explain: “large deviations from normal precipitation and mild temperatures systematically increase the risk of many types of conflict,often substantially, and that this relationship appears to hold over a variety of temporal and spatial scales.” It works in reverse, too; if there’s a sharp decrease in an area’s average temperature it can lead to increased conflict.

The next time you walk outside on a sunny day, or bundle up on a cold one, pay attention to what you want to do. You might just find yourself compelled by some of these behaviors.

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